1. Field of the Invention
The present invention relates to flow meters; and more particularly to a method and apparatus for calibrating a flow meter having an array of sensors arranged in relation to a pipe that measures a flow rate of a fluid flowing in the pipe.
2. Description of the Related Art
Volumetric flow measurement plays a critical role in process optimization and control of most industrial processes. The current industrial flow measurement market is often segmented into two broad technology categories: old technology and new technology flow meters. Old technology flow meters include flow measurement technologies that have been in used for greater than 70 years and include turbine meters, orifice plates and variable area flow meters. The new technology flow meters have emerged over the last 30˜50 years and offer advantages over the old technologies in performance, functionality, and reliability. The major types of new technology flow meters include ultrasonic meters, electromagnetic flow meters, vortex flow meters, and coriolis flow meters. Each type has evolved to serve various aspects of the diverse range of applications within the industrial flow meter landscape. For example, the electromagnetic flow meter has emerged as the dominate type of flow meter used in the paper and pulp industry.
In particular, flow meters having an array of sensors arranged in relation to a pipe that measure a flow rate of a fluid flowing in the pipe are known in the art. For example, U.S. Pat. No. 6,609,069, which is incorporated by reference, discloses a method and apparatus for determining the flow velocity of fluid within a pipe, such as an oil pipe.
One problem with flow meters in the art is that, despite the fact that they are calibrated to measure a flow rate of a given fluid(s) flowing in a given pipe(s), this calibration may not be correct when the flow meter is used in the field to measure different types of fluids flowing, for example, in different types of pipes than those in which the flow meter was originally calibrated to measure fluid flow. For example, the original calibration is likely to provide an incorrect measurement when the flow meter is used in relation to a fluid having a different density or viscosity than it was originally calibrated, or when the flow meter is used in relation to a pipe having a different wall thickness or inner diameter than it was originally calibrated, or when the array of sensors are spaced differently in relation to the pipe than it was originally calibrated. In view of this, the known flow meters are likely to have an error in their measurement, for which no correction is made. Moreover, the known flow meters are not designed to correct the original calibration based on one or more parameters that characterize either the array of sensors, the pipe, the fluid flowing in the pipe, or some combination thereof.
There is a need in the prior art for a flow meter that can be calibrated in the field based on receiving such parameters.